Does dementia run in families?

Genetics and dementia

Damage to a person’s brain cells causes dementia symptoms. The damaged brain cells cannot communicate as they usually do with one another, leading to symptoms of the condition.

Different types of dementia brain cell damage have different root causes. Some genes can cause the development of brain cell damage that leads to conditions such as Alzheimer’s disease.

Genes are instructions in a person’s DNA that control a person’s characteristics, such as eye color and height. Biological parents pass their genes down to their children.

Inheriting certain genes can increase a person’s risk of developing forms of dementia, such as Alzheimer’s. However, having these genes does not guarantee someone will develop the condition.

Researchers have identified some rare genes that may cause forms of dementia, including Alzheimer’s. APOE-e4 is a gene that carries the strongest effect on susceptibility to Alzheimer’s disease. According to the Alzheimer’s Association, 40-65% of people with an Alzheimer’s diagnosis have this gene.

There are other inheritable gene mutations that almost guarantee someone will develop Alzheimer’s. These gene mutations include amyloid precursor protein, Presenilin 1, and Presenilin 2.

Having any of these genes may increase the risk of Alzheimer’s symptoms appearing early on.

However, this condition does not typically have a single genetic cause, as multiple genes and lifestyle factors can influence a person’s risk. People can also develop Alzheimer’s without having a family history.

Another type of dementia that has strong genetic links is Huntington’s disease. This is a condition that causes a gradual breakdown of the nerve cells or neurons in the brain.

Frontotemporal dementia is an uncommon type of dementia. However, health experts believe it also has strong genetic links. Around 1 in 8 people with frontotemporal dementia have family members who also had the condition. This type of dementia affects people’s behavior and language.

Ways to test for dementia

There is no one test for dementia. Doctors start with a physical exam, including checking the person’s vital signs. This helps assess whether they have an underlying condition causing cognitive difficulties.

Doctors will also review the individual’s medical and family history to check for dementia risk factors. Diagnosis may also involve tests such as:

• cognitive and neurological tests that assess a person’s thinking, language, and memory skills
• brain scans to identify strokes, tumors, and other problems that can cause dementia
• psychiatric evaluations
• cerebrospinal fluid (CSF) tests to measure the levels of proteins or other substances in CSF that may indicate Alzheimer’s or other types of dementia

Doctors also can test people for the genes that may cause dementia.

Other causes of dementia

Conditions that cause dementia symptoms include:

• Alzheimer’s disease
• frontotemporal dementia
• Lewy body dementia
• vascular dementia

People may also have combinations of two or more types of dementia conditions, which doctors call mixed dementia.

Preventions and treatments of dementia

There is no cure or treatment that can prevent dementia. However, people may be able to reduce their risk of developing the condition by:

• controlling or treating high blood pressure
• keeping their blood sugar within certain levels
• eating a nutritious diet that includes:
  • fruits and vegetables, whole grains, lean meats, and seafood
  • unsaturated fats such as olive oil, low fat or nonfat dairy products
• staying physically and mentally active
• preventing social isolation and loneliness by staying connected with family and friends
• treating hearing problems and hearing loss
• preventing or avoiding head injuries
• drinking less or no alcohol
• quitting or avoiding smoking

Doctors can also prescribe medication to manage dementia symptoms, such as anxiety or behavior changes.

Frequently asked questions

The following are some questions people frequently ask about dementia.

How likely is someone to get dementia if it runs in their family?

People with a parent or sibling with Alzheimer’s disease have an increased risk of developing it themselves. Their risk increases again if more than one biological parent or sibling has Alzheimer’s.

According to the Centers for Disease Control and Prevention (CDC), having a close relative with Alzheimer’s increases a person’s risk of developing it by 10–30%. Alzheimer’s is the most common cause of dementia.

Who is most at risk for dementia?

Although getting older does not cause dementia, age is the most significant risk factor for common causes, such as Alzheimer’s. About one-third of all people 85 years or over may have Alzheimer’s disease.

What can trigger dementia?

According to a 2020 report from the Lancet Commission, risk factors or triggers for dementia can include:

• lower levels of education
• having high blood pressure, which doctors call hypertension
• having hearing impairment
• smoking
• having depression
• being physical inactive
• having diabetes
• having low social contact
• excessive alcohol consumption
• traumatic brain injuries
• air pollution

What side of the family does dementia come from?

People can inherit the genes linked to Alzheimer’s disease from either biological parent.

What can families do to avoid dementia?

There is no way to avoid dementia completely. However, avoiding triggers and following certain lifestyle habits can help reduce a family’s dementia risk.

Summary

Dementia can run in families. However, people can develop symptoms without having a family history of dementia.

Although there is no cure for dementia, lifestyle changes may help reduce a person’s risk of developing it. Additionally, medication can help manage symptoms in people who develop the condition.